Current nursery container production practices of ornamental plant material present considerable expenses for labor, construction, and water management. For example, it is general practice to water container plant material ranging in sizes from 1 gallon to 5 gallon under overhead irrigation to create a rain-like effect. However, overhead watering practice is being challenged due to environmental issues of water management for container nurseries along with increasing water shortage issues.
Under current overhead watering practices (Best Management Practices: Guide for Producing Container-Grown Plants (1997—Southern Nurserymen's Association)), irrigating 1 acre of container plant area with 1 inch of water requires 27,000 gallons of water. Of these 27,000 gallons, 90% (24,310 gallons) is wasted as run-off. Under environmental regulations, this run-off can require a collection basin to collect about 90% of the applied irrigation water per acre of container area.
Irrigation run-off from using overhead watering thus creates a need to implement costly water management practices. Such water management practices include: area stabilization (erosion), collection basins, management of storm water run-off, management of pesticide run-off, management of nutrient extraction (nitrogen & phosphorus leaching), management of liquid fertilizer run-off, management of recycled run-off water for irrigation use and management of culverts and ditches.
While new management practices in growing 1 to 5 gallon container plant material are being implemented, there has been limited advances in reducing run-off, water usage, labor cost, environmental concerns and construction costs. In traditional 1 to 5 gallon container growing, a potted plant is placed on top of a plastic or combination of plastic and weed mat barrier or gravel beds. The plastic stops the water that falls from the overhead sprinkler head or rain from absorbing into the surrounding soil that the container plants are placed on. This practice moves water away from the growing area to keep the planting area dry during times when the plant is not being watered. The plastic controls weeds in the growing area.
Over the years, growers found themselves having to replace the plastic due to solar breakdown, tearing and certain weed penetration through the plastic. In recent growing practices, growers are now incorporating a weed mat barrier over the top of plastic. This weed mat barrier is a woven type of polyethylene and/or polypropylene type material that allows water to pass through but does not break down under extreme solar conditions, does not tear easily, and weeds cannot penetrate it. The mat barrier therefore can last for several years.
By installing the plastic underneath the barrier, irrigation and rain water are able to flow away from the growing area and standing water is reduced. This result is beneficial as standing water in growing areas increases the chance for fungal diseases in the growing area. However, this type of growing practice over large areas requires that an extreme amount of irrigation and storm water run-off be managed in compliance with environmental standards.
Other growing practices incorporate growing potted plants on gravel beds, but these practices are very costly. In addition, gravel beds used in sandy regions do not control weeds in growing areas due to rapid leaching of pre and post herbicides.
Current growing practices thus are highly limited by the extensive amounts of construction cost needed to excavate the growing areas to contain run-off of irrigation and storm water. Accordingly, there is a need for an environmentally-friendly plant-production method that significantly reduces the time and costs of water management construction activities.